(1) Field of the Invention
The present invention relates to a particle mobile type image display device such as an electrophoresis display device and the like which switches the display state with pigmented particles moving in a solvent.
(2) Description of Related Art
WO 99/53373 discloses a color reflection display device including two kinds of pigmented phoretic particles being different in charging property and pigmentation filled inside a unit cell so as to move the two kinds of pigmented phoretic particles independently by applying voltage to three drive electrodes to display three colors of two kinds of pigmented phoretic particles and electrophoresis liquid color or three colors of two kinds of pigmented phoretic particles and color filter color arranged on the rear side of the unit cell. That display device is described to take white particles and pigmented color particles as two kinds of pigmented phoretic particles and adopts a color filter establishing relation of complimentary color with the pigmented color particles and thereby display four colors of white, black and the color of the pigmented color particles and the color of the color filter. Moreover, it is described that color display is implemented in use of three sub pixels different in display color with a unit cell being a sub pixel.
JP-A-2004-20818 discloses an electrophoresis display device having a pixel configuration by arranging, in a stacked arrangement or in a parallel arrangement, unit cells including two display electrodes arranged in approximately overlapped positions in a view from an observer, two collect electrodes and two kinds of transmissive pigmented phoretic particle presenting mutually different charging polarity and color presentation. That display device displays four colors of white, black and two kinds of colors of transmissive pigmented phoretic particle in a unit cell by combining red, green and blue for transmissive pigmented phoretic particles or combing cyan, yellow and magenta establishing relation of complimentary color with red, green and blue to arrange white scattering layer in a display electrode portion. In addition, likewise WO 99/53373, it is described that color display is performed using three sub pixels different in display color with a unit cell being a sub pixel.
However, in the display device of WO 99/53373, two of the three drive electrodes are electrodes for collecting particles arranged on the same substrate. It is necessary to arrange those electrodes to provide a large spacing in between in order to display the color of a color filter with high luminance. On the other hand, in order to display the colors of particles sufficiently, it is necessary to arrange the particles to spread between those electrodes. However, it is difficult to arrange the drive force to act so as to spread the particles between the two drive electrodes with three drive electrodes. It is considered to give rise to a problem that the particles do not spread well between the electrodes or response time gets long.
The display device in JP-A-2004-20818 adopts four electrodes, there have been problems that independent drive thereof and, in particular, the drive method, the drive circuit and the electrode wiring of two electrodes provided on the substrate on the light incident side become complicated.
In addition, in any display device, color display is implemented with three units of sub pixels. Therefore, the portion of the bulkheads and the capsule wall for separating the sub pixel will become abundant to increase the portion not contributing to the display operation and to make aperture ratio small, giving rise to a problem that reflection percentage drops or contrast drops. Moreover, there were such a problem as well that fine division into sub pixels makes process accuracy severe and the number of wiring gets abundant or the number of drive device gets abundant in active drive provided with a drive device in each sub pixel.
In addition, also in any display device, at least two electrodes are arranged in parallel in the same layer of the same substrate and, therefore, are required to be arranged to provide spacing between the electrodes. That spacing portion does not contribute to the display operation, giving rise as well to a problem of dropping reflection percentage or dropping contrast.
The problem to be solved by the present invention is to realize an electrophoresis display device in a simple configuration with high reflection index or transmission rate and contrast.